This disclosure relates to a method and system for servicing a wellbore and preparing an improved cement. More specifically, this disclosure relates to a method and system for servicing a wellbore with cement compositions comprising electrochemically activated water.
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe, e.g. casing, is run in the wellbore. The drilling fluid may then be circulated downward through the interior of the pipe and upward through the annulus, which is located between the exterior of the pipe and the walls of the wellbore. Next, primary cementing is typically performed whereby a cement slurry is placed in the annulus and permitted to set into a hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal the annulus. Subsequent secondary cementing operations may also be performed. Secondary operations may include remedial cementing, squeeze cementing, plug-to-abandon cementing, or kick-off plug cementing.
A particular challenge in cementing is the development of satisfactory mechanical properties in a cement slurry within a reasonable time period. During the life of a well, the subterranean cement sheath undergoes numerous strains and stresses as a result of temperature effects, pressure effects, and impact effects. The ability to withstand these strains and stresses is directly related to the mechanical properties of the cement. The mechanical properties of a cement are often characterized using parameters such as compressive strength, tensile strength, Young's Modulus, Poisson's Ratio, elasticity, and the like. These properties may be modified by the inclusion of additives. For example, chemical accelerators such as sodium chloride may be added to cement slurries to obtain rapid setting of the cement and the development of compressive strength, while strength-enhancing additives such as silica flour can be used to ensure adequate compressive strength and long-term structural integrity of the cement. In some instances, fibers may be included to enhance the tensile strength of the set cement. In still other instances, polymeric elastomers may be included to enhance the elastic properties (often described by Young's Modulus and Poisson's Ratio) of the set cement. However, there are often drawbacks to the inclusion of such additives to the cement slurries. For example, the addition of an excessive amount of accelerator has resulted in cement slurries that stay in liquid form and never gain any compressive strength. In the case of the addition of fibers or elastomers to the cement slurry, these additives may rapidly form viscous gels with a premature loss of pumpability. In other cases, these additives may impart an undesired impact on cement slurry density. For example, the addition of polymeric elastomers may drastically reduce the overall cement slurry density and make it difficult to achieve a target density. Thus, a need exists for cement compositions with enhanced mechanical properties that maintain desirable features such as rheology (i.e. how a fluid responds to stresses and strains), pumpability, viscosity, setting time, density, and other features desirable to those skilled in the art.